HCV Triple Therapy Trial

SciClone’s European partner, Sigma-Tau, currently is enrolling up to 550 HCV non-responder patients in a phase 3 clinical trial in Europe to evaluate the use of ZADAXIN as part of a triple therapy combination (ZADAXIN, pegylated interferon and ribavirin). Patients enrolled in this trial will receive 48 weeks of therapy followed by a 24-week observation period to assess the achievement of sustained virologic response (SVR), which is measured at week 72. Sustained virologic response is defined as the lack of detectable levels of viral RNA in the bloodstream 24 weeks after the completion of 48 weeks of treatment. If a patient is able to achieve an SVR, he or she is typically considered to be cured of HCV.

The basis for this European triple therapy trial is encouraging data that SciClone achieved from a small, single-arm triple therapy pilot trial. Final results from this trial showed that 20% (6/30) of patients treated with ZADAXIN, pegylated interferon alpha and ribavirin achieved an SVR.

This HCV trial is different in two important ways from SciClone’s U.S. phase 3 HCV trials. First, patients in this trial are being treated with the anti-viral agent ribavirin in addition to ZADAXIN and pegylated interferon alpha (the only two drugs used in SciClone’s U.S. phase 3 trials). Second, patients in this trial are previous non-responders to the combination of pegylated interferon alpha plus ribavirin, compared with the diverse group of non-responder patients who were enrolled in the U.S. phase 3 trials non-responders to any interferon-based therapy in the U.S. phase 3 trials.

U.S. HCV Phase 3 Trials
In December 2005 and May 2006, SciClone reported final results from its two U.S. phase 3 trials in HCV non-responder patients. Results from the first trial did not show a statistically significant benefit from treatment with ZADAXIN and pegylated interferon alpha compared to treatment with pegylated interferon alone in sustained viral response (SVR) or histologic improvement, the trial’s’ co-primary endpoints. Similarly, results from the second trial did not show a statistically significant benefit from treatment with ZADAXIN plus pegylated interferon alpha compared with pegylated interferon alpha alone in SVR. ZADAXIN was well tolerated with few reports of significant side-effects or toxicities.